This invention relates to apparatus for dispensing predetermined amounts of liquid by weight into a container and, in particular, is directed toward an improved apparatus and method for dispensing liquid into a container of the type shown in commonly-assigned U.S. Letters Pat. Nos. 4,211,263, 4,337,802 and 4,494,583, said patents and their respective disclosures are hereby incorporated by reference.
Depending upon the nature of the liquid, any of several filling techniques may be utilized to dispense a predetermined, metered amount of liquid into a container, typically a 55 gallon drum. If the liquid is susceptible to foaming, toxic or expells noxious fumes, it is typically the practice to insert a filling lance (the conduit through which the liquid passes into the container) into the container such that the lower discharge end of the lance is in close proximity to the bottom of the container.
The movement of the filling lance, sometimes referred to as a conduit, is initiated by the operator of the filling apparatus. In the preferred filling apparatus utilized in conjunction with the bung engaging tool of this invention a predetermined small amount of liquid is slowly introduced into the container until the level of liquid in the container rises above the discharge end of the lance. Since the discharge end of the lance is thereafter below the level of liquid in the container, most of the remaining volume or weight of the liquid may be introduced into the container at a relatively faster fill rate until the fill rate is decreased (to a dribble fill rate) just before the final weight of liquid has been dispensed. During the fast fill operation, the lance is incrementally withdrawn from the container, but at a rate which maintains the end of the lance below the liquid surface in the container. The withdrawal of the lance is generally controlled by the operator in order to maintain the discharge end of the lance below the liquid fill surface.
Once the predetermined amount of liquid has been introduced into the container, the lance is fully withdrawn. Upon completion of the fill cycle with previous drum filling apparatus, the container would normally be conveyed along the line to another station where the container would be capped or the bung inserted.
A disadvantage of existing commercial systems is that there is no means for automatically removing or inserting the bung cap other than manually. Attempts to automate the process have met with substantial problems in that different brands and types of bung caps are shaped differently and require unique tools for removal and insertion. Prior attempts to design bung insertion and removal apparatus have met with mechanical failure rates below that which are considered acceptable. The novel apparatus of this invention permits the automatic handling of bung caps without requiring operator intervention. Bung caps can now be automatically removed and reinserted during the drum filling sequence.
When working with toxic or noxious liquids, it is desirable to have the container immediately capped as soon as the filling operation is completed, rather than capping the container at another station. Therefore, apparatus that removes a bung from a container prior to filling operations and replaces the bung immediately after filling operations are completed is desired. Such apparatus is desirable for any liquid, but is considered essential for toxic or noxious chemicals.